A twenty-three-year-old worker sustained a blast injury to the right thigh when a high-pressure pipeline burst, resulting in a grade-IIIB open comminuted femoral fracture8,9; loss of the vastus lateralis, the iliotibial band, the biceps femoris, and 7 cm of the femoral diaphysis (Figs. 1-A and 1-B); and severe impairment of peroneal nerve function. The patient underwent multiple débridements, skin-grafting, femoral nail fixation, and bone-grafting before the femoral fracture eventually healed. Limb length was subsequently restored through 7 cm of distraction osteosynthesis. The patient was able to walk with use of an ankle-foot orthosis as treatment for the peroneal nerve palsy; however, despite the use of a custom-made knee orthosis, he continued to be bothered by knee instability.
Two years after the injury, the patient walked with the knee severely internally rotated and used a cane due to the knee instability. Examination revealed a knee range of motion of 5° to 120°, a 5° quadriceps lag, and mild patella infera. The Lachman test was negative, but results of the anterior tibial drawer test indicated increased anterior translation of the lateral tibial plateau when the knee was positioned in 90° of flexion. With the knee positioned in 90° of flexion, the affected knee had almost no passive or active external rotation of the tibia on the femur, whereas the contralateral knee had 30° of external rotation. There was mild laxity in the lateral ligaments, which was believed to be due to stretch of the lateral ligaments of the knee from repeated weight-bearing stress and from the mild varus alignment of the knee that could be seen on weight-bearing radiographs and that was possibly due to mild tibia varum (Fig. 2). The femoral fracture was well aligned. The biceps femoris, iliotibial band, and vastus lateralis were absent. Active ankle dorsiflexion was absent, and peroneal muscle strength was grade 1 (of 5) with good plantar flexion strength. A hip-knee computed tomographic scan confirmed that femoral rotational alignment was normal. The internal rotation contracture of the knee was believed to be a result of the unbalanced rotational moments on the knee (absent external rotators and active internal rotators) and possibly due to scarring of the muscles at the medial aspect of the thigh.
The combination of mild laxity at the lateral aspect of the knee and tibia varum was treated with a 1.5-cm proximal medial opening-wedge valgus osteotomy of the tibia with use of allograft bone to fill the resultant defect and was then fixed with a locking osteotomy plate (TomoFix; Synthes Trauma, West Chester, Pennsylvania) (Figs. 3-A and 3-B). The osteotomy increased the tibial slope from 10° to 15°. Seven months later, the limb alignment was improved but complaints of rotatory instability continued and the patient walked with the knee internally rotated. The most likely cause of the persistent rotatory instability was an imbalance between the internal and external rotator muscles due to loss of the biceps femoris. Since the semitendinosus originates from the ischial tuberosity adjacent to the long head of the biceps femoris and follows a similar course to the proximal aspect of the popliteal fossa, it seemed reasonable to transfer it to the lateral side of the knee to restore muscle balance. The gracilis, which lies just medial to the semitendinosus at the proximal end of the popliteal fossa, also seemed to be a reasonable candidate for transfer. Both of these tendons lie posterior or medial to the neurovascular bundle in the thigh. Subcutaneous tunneling of the tendons in the distal portion of the thigh from medial to lateral, and then to the lateral aspect of the knee, would position them safely posterior to the neurovascular bundle (Fig. 4).
Three years after the original injury, plate removal and soft-tissue reconstruction were done. The uniqueness of the injury, the vascular and neurological risks of surgery, and, specifically, the information that this operation had not been done before were thoroughly discussed with the patient over the months preceding the surgery. Medial and lateral longitudinal incisions were made from the distal aspect of the thigh to the knee. The osteotomy plate was removed, and the gracilis and semitendinosus tendons were detached from their insertion sites. Nonabsorbable, number-2 locking sutures were placed in the tendon ends. The tendons were dissected proximally and freed from their other insertions, then passed subcutaneously, first posterior to, and then lateral to, the protected neurovascular structures. A 6.5-mm tunnel was drilled in the fibular head, starting at the posterior aspect of the fibular head and exiting at the anteromedial aspect. The two tendons were then passed through the tunnel, and their sutures were tied to a screw placed in the anterolateral aspect of the tibia (Fig. 5). Although the tension that was applied during tendon fixation was not quantified, it was similar to that experienced during reattachment of an avulsed biceps tendon. The peroneal nerve lay distal to the transfer and thus was not at risk of compression during tensioning. Postoperatively, a circumferential fiberglass long leg cast that held the knee in external rotation and at 45° of flexion was applied to reduce strain on the repair during the early stages of healing.
At the two-week postoperative visit, the cast was changed to a custom-made knee-ankle-foot orthosis, which held the knee in flexion and external rotation. At the four-week postoperative visit, the patient was allowed to start passive flexion and active extension exercises; however, to minimize the strain on the transferred tendons, the knee was kept in external rotation with use of the orthosis. No weight-bearing was allowed until comfortable extension was achieved at two months postoperatively.
Eight months later, to stabilize the foot, a posterior tibial tendon transfer to the lateral aspect of the foot was performed in conjunction with toe-tendon transfers and tendon-lengthening.
Examination one year after the combined gracilis and semitendinosus tendon transfer (four years after the injury) revealed extremity shortening of 1 cm and patella infera, with the distal pole of the patella lying at the level of the tibial plateau. The knee had an active range of motion from 0° to 125°. There was no swelling. The Lachman test, the pivot-shift test, and the reverse pivot-shift test were all negative. There was residual mild laxity of the lateral ligaments of the knee, which was unchanged from that seen preoperatively. The dynamic anterolateral rotatory knee instability was gone, and the patient was satisfied with the improvement in gait and with the stability of the knee. He walked in the community without a knee brace and could do light jogging. With a custom knee brace, he participated in noncontact martial arts.
Note: The authors acknowledge Dr. Richard Buckley, who performed the trauma surgery and femoral lengthening, and Dr. Iain Russell, who performed the foot surgery on this patient.